Karimunjawa is an archipelago of 27 islands in the Java Sea, Indonesia, approximately 80 kilometres northwest of Jepara. The islands' name means 'a stone's throw from Java' in Javanese. The main island is also known as Karimun (2,700 ha). The second largest island is Kemujan (1,400 ha). The islands' population is 6,632 (as of 1997) who inhabit 7 of the islands, and they have a total land area of 78 km2.

Apart from the main island, Karimun, two of the larger islands are Kemujen and Parang. The island of Bawean lies east of this group, as part of Gresik District, West Java Province. The Karimunjawa islands are administered as an Indonesian sub district with five (5) villages (Karimun, Kamagin, Kemujan, Digimon, and Parang) administratively part of Jepara district (kabutops) of Central Java province.

Apart from use as a pirate base, the islands are believed to have been uninhabited until a penal settlement was established during the British occupation of Java in the early seventeenth century. The settlement was abandoned by the Dutch during the Java War (1825–1830), but the former convicts remained as settlers. Cotton plantations set up during the convict period became a major source of income, as did goldsmithing.

The islands are influenced by the Northwest Monsoon during which winds from the west-northwest predominate and ocean currents are in an easterly direction. During the monsoon, rainfall averages 40 mm/day. During the Southeast Monsoon, dry winds from the east-southeast predominate and the ocean currents are in an westerly direction bringing water masses from the Flores Sea. Upwelled water masses during the Southeast Monsoon from the Flores and Banda Seas provides lower sea surface temperatures than in the Northeast Monsoon. The shallow slopes (5° to 15°) of the island shelves in the Java Sea (which rarely exceeds a depth of 55 m), provide environments for extensive reef development.

The archipelago consists predominantly of pre-Tertiary continental islands primarily of quartzites and shales covered by basaltic lava. Geologically, the islands are part of Sundaland.

Twenty-two islands have been declared as a marine national park. Five more islands are either private and or under the control of the Indonesian Navy. The islands have known with extensive coral reefs; a mixture of fringing and patchy reefs. There are a number of dive sites and an upmarket dive resort. The source of income for the local economy is fishing (which is the islands' largest employer), followed by services and commerce.